1. Field of the Invention
The present invention relates to a mobile communication system and more particularly to an apparatus and method for communicating data using a code division multiple access (CDMA) system in a CDMA cellular phone.
2. Description of Related Art
The CDMA system, which is one of multiplex operation systems, makes multiple mobile stations share frequency and time and allocates a pseudorandom sequence to each mobile station. The mobile station at a transmitting party spreads transmitting signals through the pseudorandom sequence to transmit the signals. The mobile station at a receiving party generates the same pseudorandom sequence as that used at the transmitting party to synchronize received signals and despreads the received signals to recover the signals.
The CDMA system employing a band spread communication technique that has been basically used for a long time considerably enhances efficiency in using frequency in addition to all advantages of the band spread communication technique. In other words, since the same frequency band can be used in all service areas, in the aspect of the cellular concept, a frequency reuse coefficient is xe2x80x9c1xe2x80x9d, so the CDMA system effects much higher frequency use efficiency compared with other communication systems. Soft handover can also be accomplished because the same frequency band can be used in all service areas. Furthermore, the CDMA system ensures an excellent privacy communication feature in a radio communication section since it uses different codes for each communication.
FIG. 1 is a block diagram showing a configuration of a conventional CDMA cellular phone. As shown in FIG. 1, RF/analog sub-system 102 performs frequency synchronization of received signals and power control of transmitting signals and also generates system clocks. Baseband analog (BBA) 104 comprises up/down converter and filter, a D/A converter, and an A/D converter. The baseband analog 104 processes voice data that is not modulated. Mobile station modem (MSM) 106 comprises CDMA demodulator 108, interleaver modulator 110, and Viterbi decoder 112. The CDMA demodulator 108 demodulates the received signals. The interleaver modulator 110 modulates and sends the transmitting signals to the baseband analog 104. The Viterbi decoder 112 compensates the received signals for errors. Universal asynchronous receiver transmitter (UART) 118 is an input/output interface connecting to exterior devices.
Such conventional CDMA cellular phone does not have a function of receiving Global Positioning System (GPS) data. If the function of transmitting and receiving the GPS data is added to the conventional CDMA cellular phone and calculation of location information from received GPS data is allowed, a user can transmit his/her location information to a base station or another user through the CDMA cellular phone and receive GPS data from the base station to appreciate his/her present location, thus doubling the value of the conventional CDMA cellular phone.
Accordingly, the present invention is directed to a GPS data controller in a mobile communication system and a control method thereof that substantially obviates one or more of the limitations and disadvantages of the related art.
An objective of the present invention is to provide a mobile communication system which can transmit and receive GPS data by adding a buffer for storing the GPS data and a memory for storing location information of a base station and controlling the system through a central processing unit (CPU).
Additional features and advantages of the invention will be set forth in the following description, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure as illustrated in the written description and claims hereof, as well as the appended drawings.
To achieve these and other advantages, and in accordance with the purpose of the present invention as embodied and broadly described, a mobile communication system comprises a signal processor, a first memory, a controller, and an input-output controller. The signal processor receives first forward GPS data and transmits backward GPS data. The first memory has a preamble area, a base station information area, a time information area, and a location information area and stores the backward GPS data, the first forward GPS data, and second forward GPS data received by an exterior GPS receiver. The controller controls data input and output over the first memory and controls transmission of the backward GPS data stored in the first memory to the signal processor. The input-output controller is controlled by the controller and transmits the second forward GPS data to the first memory.
In another aspect of the present invention, a data transmitting method of a mobile communication system has a first mode and a second mode. In the first mode, GPS data stored in a GPS data memory is transmitted to a preselected telephone number. In the second mode, the GPS data is transmitted to a telephone number currently connected for communication in a GPS transmitting mode.
In further another aspect of the present invention, a data receiving method has a first mode and a second mode. In the first mode, time information and location information from a GPS receiver is displayed via an exterior display unit when the GPS receiver is connected. In the second mode, at least three pieces of GPS data are received from different base stations, time information and location information is calculated from the received GPS data, and the information is displayed via the exterior display unit when the GPS receiver is not connected.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.